Combustion apparatus



G. BROLA COMBUSTION APPARATUS April 24,' 1962 Filed Dec. 29, 1958INVENTOR.

GABRIEL BROLA ATTORNEY 3,031,012 CUMBUSTION APPARATUS Gabriel Brola,Bourg-la-Rcine, France, assignor to Generaie Thermique-Procedes Brola,Societe Anonyrne,

Le Pre Saint-Gervais (Seine), France Filed Dec. 29, 1%58, Ser. No.783,486 Claims priority, application France Dec. 27, 1957 1 Claim. (Cl.158-46) This invention relates to combustion apparatus of the generaltype including a concave-convex or dome-shaped shell member formed witha central air and fuel inlet opening and spaced side openings forsecondary air, an injection nozzle being positioned axially of the shellat the convex side of it to direct divided fuel through said centralinlet thereof, and saidshell being associated with a preferablyfrustoconical annular wall in surrounding spaced relationship therewith,the shell and annular wall being interconnected by an annular set ofangularly spaced generally radial fins having cross sectional contoursin the general form of an inverted V and defining therebetween auxiliaryor tertiary air inlet apertures, whereby a highly turbulent combustionZone becomes established within the annular wall at a point spaced fromthe concave side of the shell.

Such combustion apparatus has been disclosed in my co-pending U.S.Patent application Ser. No. 548,491 filed November 22, 1955, and whichhas issued as Patent No. 2,901,032, and in the form specificallydescribed therein, the shell comprises an axial air inlet in the shapeof a converging-diverging nozzle, and further, the fins are shown asbeing symmetrical about the radial midplane of each fin. The objects ofthe'present invention are to provide modifications in the design of the,air inlet and fins of combustion apparatus of the type disclosed in mysaid co-pending application, whereby the operating efficiency thereofwill be substantially improved.

According to one feature of the present invention, the central inletaperture in the shell is provided in the form of a simple wall-lessaperture rather than a nozzle with converging-diverging walls,'anddeflector means are associated with said inlet at a point axially spacedtherefrom towards the convex side of the shell, arranged to impart arotational motion to at least part of the air admitted into the inlet.

In one embodiment, the deflector may be provided by a frustoconical discformed with a central aperture and connected with the shell around theinlet aperture thereof by an annular set of vanes extending at an angleto the radial midplanes thereof so as to impart said rotational motionto the air. In such a construction, part of the air entering the shellthrough its central inlet aperture is caused to flow axially through thedeflector, while the remainder of the air is caused to flow through thespaces between the vanes. The impact between the axial and thetangential air flows creates a high turbulence centrally of thedeflector and near the apex of the shell and such turbulence promotesignition of the mixture.

According to another feature of this invention, the fin elementssurrounding the shell and interconnecting its outer edge with theannular frustoconical surrounding wall, rather than being symmetricalabout radial planes, are also angled with respect to such radial planes,the angle being conveniently in a range of from 20 to 40 and preferablyabout 30. This arrangement results in a dissymmetrical pattern ofalternating vortices at the roots of the fin elements whereby suchvortices will interact energetically with one another to produceintimate fuel-air mixes. The area at which the flame front stabilizes isthus made more regular and more uniform.

Preferably moreover, one of the side walls of each fin element is madeto deviate; in a portion adjacent the root of the fin, so as to extendsubstantially parallel to the adjacent side wall of the adjacent finelement. This enhances the discharge of the vortex at the root of thefin.

A preferred form of construction of the improved combustion apparatus isillustrated by way of example in the accompanying drawings, wherein:

FIG. 1 is an axial sectional view of the apparatus;

FIG. 2 is a cross sectional developed view of the fin elements on theline II--II of FIG. 1;

FIG. 3 is an axial view of the deflector; and

FIG. 4 is a plan view thereof.

As shown in the drawings, the combustion apparatus of thisinventioncomprises a dome-shaped shell member 1 having spaced holes 3and 4 of predetermined diameter formed in its wall and an air'inletaperture to be presently described formed in the small-diameter end ofthe dome-shaped shell member. Extending from the largediameter end ofthe shell member are an annular set of angularly spaced fin elements 6which extend generally radially with respect to the central axis ofshell member 1 and have their outer ends joined to a frustoconicalannular wall 7 disposed at the entrance end 13 of a furnace tube 12.Associated with the air inlet aperture at the top of the shell is anaxially positioned fuel injection nozzle l4 and, to a side thereof, anigniter device 15.

The air inlet is formed as a simple circular aperture 2 and a deflectoris positioned thereabove. The deflector comprises a frustoconical disc21 with a circular opening 22 at its apex and fins 23 extending from itsunder side into engagement with the part of the shell 1 surrounding itsaperture 2'. The fins 23 though positioned generally radially, arenevertheless not strictly radial in extent but form a comparativelysmall angle with respect to the radial planes, as clearly shown in FIG.4. The deflector disc 21 is connected to the injector 14 by way ofradial arms 24.

The outer fins 6 between the shell and the annular wall 7 are likewiseinclined at a definite angle, of about 30, with respect to radialplanes, as will be apparent from FIG. 2. Moreover, the sloping side ofeach fin 6 has a minor root portion thereof deflected as indicated at 25so as to extend substantially parallel to the adjacent side of the nextfin. Hence the spaces 11 between the fins 6 which spaces form inlets forauxiliary or tertiary air, each include a converging or tapering mainsection followed by a minor end section or duct 26 of constant sectionarea. The fins 6 are generally of elongated triangular contour as shownand are rounded at their apex as shown at 8, whereas both root apices 9and 10 are sharp-edged as shown. These apices 9 and 10 are furtherinterconnected by arcuate concave wall portions 20.

In operation, combustion air entering the shell member 1 by way of airinlet 2, first passes the deflector disc 21. flector disc by way of thecentral aperture 22 thereof. Another part of the air flows tangentiallypast the deflector disc by way of the spaces between the vanes 23. Asthe two air flows impinge against-each other in a central region forwardof the deflector disc a zone of high turbulence is there created andinto this zone the fuel from injection nozzle 14 is injected. Owing tothe turbulence, the fuel is subjected to vigorous mixing, therebyproviding a uniform and eflicient combustible mixture. This mixtureflows by way of air inlet 2' into the shell 1, while secondary air alsoflows into the shell through the holes 3 and 4. Vortices 16 are thusgenerated within the shell which impart further mixing to thecombustible gas mixture which finally issues from out of the shell intothe tube 12 and there mixes with the tertiary air flow dischargedthrough the spaces 11 between the fins 6.

As schematically shown in FIG. 2, alternately directed One part of thisair flows axially through the devortices 17 form at the root of the fins6, and these vortices are stripped off the sharp edges 9 and 10 by thefuel mixture issuing out of the shell member, and'are broken up andtransferred downstream into the area 27 to provide thereat amultiplicity of separate small alternately revolving vortices which arefinally damped out.

Owing to the angling of the fins 6 such vortices 17 are unsymmetrical incharacter so that they interact to produce an enhanced mixing action.The flame front which is stabilized by the vortices is thus made morestable and uniform and combustion is improved.

Various modifications may be made without departing from the scope ofthe invention.

What I claim is:

In combustion apparatus, the combination of a substantiallyhemispherical shell member having convex and concave outer and innersurfaces, respectively, and a centrally located axial air-inletaperture, a disk-like deflector member overlying said air-inlet apertureat the convex outer surface of said shell member and spaced from thelatter,said deflector member having a central opening axially alignedwith said aperture of the shell member, an annular set of vanesextending between said disk-like deflector member and said shell memberand each inclined by a small angle with respect to a plane ReferencesCited in the file of this patent UNITED STATES PATENTS 1,862,126 TernauJune 7, 1932 2,000,733 Avery May 7, 1935 2,054,162 Macrae Sept. 15, 19362,664,702 Lloyd et a1 Jan. 5, 1954 2,876,763 Hunter et a1. Mar. 10, 19552,879,836 Dumas Mar. 31, 1959 FOREIGN PATENTS 178,351 Switzerland Sept.16, 1935 679,145 Great Britain Sept. 10, 1952

